The present invention relates to a novel detergent which contains liquid sodium silicate, and more specifically, to a clear liquid detergent containing liquid sodium silicate.
Liquid detergents utilizing sodium silicate which is liquid silicate salt have been expected to latently have a far excellent detergency power than those of any other surfactants, and since long time ago, there have been enormous efforts and researches made to develop such a detergent in many industrial fields including detergent and chemical industries. However, until today, there has been n6 developmental technique established in our country or other world industrial countries.
Conventionally, for liquid detergents, alminosilicate salts such as zeolites (A-type, Y-type), crystalline alminosilicate salts, inorganic silicates, inorganic carbonates or the like have been utilized as a detergency builder, and there have been a great number of patent applications filed. However, many of liquid cleansers, liquid detergents and the like are mainly designed for cleaning dishes, kitchen and bathroom, and liquid sodium silicate is not effectively utilized.
Liquid sodium silicate exhibits a mixing hindrance to a nonionic surfactant, an anionic surfactant, a metal-chelating agent, an anti-freezing agent, various builders, moisture and the like. When it is mixed with them, the mixture exhibits an optical anisotropy due to their reaction, becomes cloudy due to changes in temperature conditions caused by heating or warming, is gelled into a sherbet state due to an abrupt change in pH, and precipitates ultramicro-crystals. Therefore, the detergent containing liquid sodium silicate has not been easy to develop. In other words, there has been no clear liquid detergent which contains liquid sodium silicate together with a surfactant, and yet does not generate precipitates, or does not become cloudy due to the temperature changes.
Thus, it is an object of the present invention to provide a clear or transparent liquid detergent which contains liquid sodium silicate together with a surfactant and which does not generate precipitates, or does not become cloudy due to the temperature changes, such detergent being unable to be provided by the conventional technique.
The present inventors have conducted intensive researches for a long period of time in an attempt to provide a clear liquid detergent containing sodium silicate, that could not have been conventionally achieved, and at last accomplished the present invention.
Thus, the present invention provides a clear liquid detergent which contains, in water, liquid sodium silicate, an alkylethersulfate salt anionic surfactant, and a polyoxyethylene alkyl or aryl ether nonionic surfactant, and which does not generate precipitates or does not become cloudy due to a change in temperatures. Such a detergent has never existed in the past.
The present inventors have found that sodium silicate, a predetermined nonionic surfactant, a predetermined anionic surfactant, and optionally or preferably, a fluorosurfactant, form, preferably in the presence of a metal-chelatinqg agent, a buffering agent, a pH adjusting agent, and a freezing/clouding inhibitor, a liquid detergent which can be dissolved into water without a mutual inhibition reaction, fully exhibits a required detergency power, and maintains transparency without regard to temperature conditions. Based on these findings, the present invention has been accomplished.
In one aspect of the present invention, there is provides a clear liquid detergent composition containing liquid sodium silicate, an alkylethersulfate salt anionic surfactant, a polyoxyethylene alkyl or aryl ether nonionic surfactant, a metal-chelating agent, malic acid (particularly preferably DL-malic acid) or citric acid, glycerin, fatty acid alkanolamide and water, and optionally, further containing a fluorosurfactant.
Further, according: to the present invention, there is provided a clear liquid detergent composition comprising 10 to 35% by:weight of (a) a sodium silicate solution containing 1 to 40 parts by weight of sodium silicate, 30 to 85 parts by weight of water, 5 to 15 parts by weight of a metal-chelating agent, 0.1 to 3.0 parts by weight of malic acid (particularly preferably DL-malic acid) or citric acid and 0.15 to 15 parts by weight of glycerin; 89.5 to 59% by weight of either (b) a surfactant solution containing 5 to 50 parts by weight of an alkylethersulfate salt anionic surfactant, 5 to 30 parts by weight of a polyoxyethylene alkyl or aryl ether nonionic surfactant and 20 to 65 parts by weight of water, or (c) a surfactant solution containing 5 to 50 parts by weight of an alkylethersulfate salt anionic surfactant, 5 to 30 parts by weight of a polyoxyethylene alkyl or aryl ether nonionic surfactant, 0.01 to 0.1 part by weight of a fluorosurfactant and 20 to 65 parts by weight of water; and 0.5 to 6% by weight of (d) fatty acid alkanolamide.
The clear liquid detergent composition of the present invention is suitable for washing clothes, and cleaning niche, toilet, bathroom including a bath tub, and it can be used for cleaning dishes when diluted.
The present invention will now be described in more detail.
Liquid sodium silicate, which is contained characteristically in the clear liquid detergent (composition) of the present invention, imparts an excellent detergency power to the detergent, together with a predetermined surfactant, which will be explained later, and is an essential component for the detergent to function as such a detergent. The clear liquid detergent of the present invention, by containing liquid sodium silicate, exhibits such an excellent and high detergency power that cannot be achieved by a conventional detergent.
As such liquid sodium silicate described above, use may be made of sodium silicate No. 1 as specified by JIS (specific gravity: 59.2 or higher (Be value at 15xc2x0 C.); silicon dioxide (SiO2): 35 to 38% by weight; sodium oxide (Na2O): 17 to 19% by weight, iron (Fe): 0.03% by weight or less,. and water-insoluble component: 0.2% by weight or less), sodium silicate No. 2 as specified by JIS (specific gravity: 54 or higher (Be at 15xc2x0 C.); silicon dioxide (SiO2): 34 to 36% by weight; sodium oxide (Na2O): 14 to 15% by weight, iron (Fe): 0.03% by weight or less, and water-insoluble component: 0.2% or less by weight), and sodium silicate No. 3 as specified by JIS (specific gravity: 40 or higher (Be at 15xc2x0 C.); silicon dioxide (SiO2): 28 to 30% by weight; sodium oxide (Na2O): 9 to 10% by weight, iron (Fe): 0.02% by weight, and water-insoluble component: 0.2% by weight or less). In general, sodium silicate used in the present invention can be represented also by formula: Na2O.nSiO2, and in the case where n=about 2 to 4, it is liquid. Apart from the JIS products or commercially available products, a prepared product obtained by mixing sodium oxide and silicon dioxide at a ratio of 1 mole of the former to 2 to 4 moles of the latter can be used. As liquid sodium silicate, JIS sodium silicate No. 2 and sodium silicate No. 3 are preferable, and in particular the silicate No. 2 is more preferable.
The surfactants used in the clear liquid detergent of the present invention are an alkylethersulfate salt anionic surfactant, a polyoxyethylene alkyl or aryl ether nonionic surfactant. Optionally, a fluorosurfactant can be further contained in the detergent of the present invention. As these surfactants, commercially available products can be used.
Preferable examples of the alkylethersulfate salt anionic surfactant are primary or secondary higher alcoholethoxysulfates and alkylphenolsulfates. Of these, primary and secondary alcoholethoxysulfates, each of which has an excellent detergency and an excellent foaming property, and is less irritative to skin, are particularly preferable.
Primary higher alcoholethoxysulfate can be represented by general formula:
Rxe2x80x94(OCH2CH2)nOSO3M
where R represents a primary alkyl group, particularly, a C12 alkyl group, M represents a cation, particularly an alkali metal such as sodium, and n represents 1 to 10. Secondary higher alcoholethoxysulfate can be represented by general formula:
R(Rxe2x80x2)xe2x80x94CHxe2x80x94(OCH2CH2)nOSO3M
where R represents an alkyl group, particularly, a C6-C10 alkyl group, Rxe2x80x2 represents an alkyl group, particularly, a C2-C4 alkyl group, M represents a cation, particularly an alkali metal such as sodium, and n represents 1 to 10.
Preferable examples of the polyoxyethylene alkyl or aryl ether nonionic surfactant are polyoxyethylene alkyl ethers (primary or secondary) and polyoxyethylene alkylphenyl ethers.
Polyoxyethylene alkyl ether can be represented by general formula:
RO(CH2CH2O)nH
where R represents an alkyl group, preferably a C8-C18 alkyl group, particularly, a C12 alkyl group, and n represents 7 to 10. Polyoxyethylene alkylphenyl ether can be represented by general formula:
Rxe2x80x94C6H4xe2x80x94O(CH2CH2O)nH
where R represents an alkyl group, preferably a C8 to C9 alkyl group, and n represents 9 to 12.
The fluorosurfactant, which is optionally or preferably mixed in the clear liquid detergent of the present invention, is a surfactant having a perfluorocarbon chain, and exhibits a very excellent surface activity at low concentrations. As the fluorosurfactant, an anionic type, nonionic type or ampholytic type can be used. Preferable examples of the fluorosurfactant are perfluoroalkylcarboxylic acid (C7-C13), perfluorooctanesulfonic acid diethanolamide, perfluoroalkyl (C4-C12) sulfonate salt (preferably, an alkali metal salt such as Li salt, K salt, Na salt or the like), N-propyl-N-(2-hydroxyethyl)perfluorooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10)-N-ethylsulfonylglycine salt (K salt or the like), monoperfluoroalkyl (C6-C10) ethylphosphoric acid ester, and the like. Of these, perfluoroalkylcarbonate (C7-C13) is particularly preferable.
In order to prepare a clear liquid detergent of the present invention, it is preferable to prepare in advance: (a) a mixture containing liquid sodium silicate, water, a metal-chelating agent, malic acid or citric acid and glycerin; and (b) a mixed surfactant solution containing an alkylethersulfate salt anionic surfactant, a polyoxyethylene alkyl or aryl ether nonionic surfactant, and water, or (c) a mixed surfactant solution containing an alkylethersulfate salt anionic surfactant, a polyoxyethylene alkyl or aryl ether nonionic surfactant, a fluorosurfactant and water. Then, to the mixed surfactant solution (b) or (c), the sodium silicate solution (a) is added gradually and mixed so as to suppress foaming, and to the obtained clear mixture, fatty acid alkanolamide as a freezing/clouding agent is added and mixed.
For the preparation of the sodium silicate solution (a), it is most preferable that water, a metal-chelating agent, and malic acid or citric acid be mixed and dissolved together, and to the resultant solution, liquid sodium silicate be added gradually and mixed, followed by the addition of glycerin.
The metal-chelating agent chelates the sodium silicate so as to capture it, thus stabilizing it. Preferable examples of the metal-chelating agent are ethylenediaminetetraacetic metal-chelating agent such as ethylenediaminetetraacetate (EDTA), tetrasodium ethylenediaminetetraacetate salt and disodium ethylenediaminetetraacetate salt, with tetrasodium ethylenediaminetetraacetate salt being particularly preferable.
Malic acid (particularly preferably, DL-malic acid) and citric acid serve to capture and stabilize the metal-chelating agent, especially an ethylenediaminetetraacetic metal-chelating agent. Malic acid and citric acid serve also as a pH adjusting agent.
Glycerin serves as a pH buffering agent, and both natural type and synthetic type can be used.
The freezing/clouding inhibitor inhibits the freezing of the clear liquid detergent of the present invention and to suppress the clouding thereof, and a fatty acid alkanolamide, which is a nonionic nitrogen-containing surfactant, is preferably used. Fatty acid alkanolamide is a condensation product of a fatty acid (preferably, C8-C18 fatty acid) such as capric acid, lauric acid, coconut oil fatty acid, myristic acid, stearic acid or oleic acid, and an alkanolamine (preferably, a C8-C18 alkanolamine) such as diethanolamine, monoethanolamine or isopropanol amine. Such fatty acid alkanolamides are commercially available.
The water used in the present invention may be any one of distilled water, purified water, ion exchanged soft water, regular tap water, ground water and the like.
In the sodium silicate solution (a), it is preferable that water be blended in an amount of 30 to 85 parts by weight. When the amount of water is less than 30 parts by weight, there is a tendency that the pH value decreases markedly, which is not preferable, whereas when it exceeds 85 parts by weight, there is a tendency that the pH value increases, which is not preferable. More preferably, water should be blended in an amount of 30 to 65 parts by weight. The metal-chelating agent should be blended preferably in an amount of 5 to 15 parts by weight. When the amount of the metal-chelating agent is less than 15 parts by weight, there is a tendency that the pH value increases, which is not preferable, whereas when it exceeds 15 parts by weight, there is a tendency that the pH value decreases, which is not preferable. More preferably, the metal-chelating agent should be blended in an amount of 5 to 12 parts by weight. Malic acid or citric acid should be blended preferably in an amount of 0.1 to 3.0 parts by weight. When the amount of malic acid or citric acid is less than 0.1 part by weight, the capturing ability for the metal-chelating agent cannot be exhibited, whereas when it is more than 0.3 parts by weight, the pH value decreases excessively, which is not preferable. More preferably, malic acid or citric acid should be blended in an amount of 0.1 to 2.0 parts by weight. Sodium silicate should be blended preferably in an amount of 1 to 40 parts by weight. When the amount of sodium silicate is less than 1 part by weight, the effect of sodium silicate cannot be fully exhibited, and the detergency effect is reduced, which is not preferable, whereas when it exceeds 40 parts by weight, alkali becomes excessive, which is not preferable. More preferably, sodium silicate should be blended in an amount of 1 to 35 parts by weight. Glycerin should be blended preferably in an amount of 0.5 to 15 parts by weight. When the amount of glycerin is less than 0.5, the buffering ability is decreased, which is not preferable, whereas when it exceeds 15 parts by weight, the viscosity increases, which is not preferable. More preferably, glycerin should be blended in an amount of 1 to 12 parts by weight.
In the mixed surfactant solution (b) or (c), the polyoxyethylene alkyl or aryl ether nonionic surfactant should preferably be blended in an amount of 5 to 30 parts by weight. When the amount of the nonionic surfactant is less than 5 parts by weight, the detergency effect decreases, which is not preferable, whereas when it exceeds 30 parts by weight, the detergency effect reaches,an equilibrium state or excessive foaming is generated, which is not preferable. It is more preferable that the polyoxyethylene alkyl or aryl ether nonionic surfactant be blended in an amount of 5 to 25 parts by weight. The alkylethersulfate salt anionic surfactant should be blended preferably in an amount of 5 to 50 parts by weight. When the amount of the anionic surfactant is less than 5 parts by weight, the detergency effect decreases, which is not preferable, whereas when it. exceeds 50 parts by weight, the cleaning detergency effect reaches an equilibrium state or excessive foaming is generated, which is not preferable. It is more preferable that the alkylethersulfate salt anionic surfactant be blended in an amount of 5 to 40 parts by weight.
In the aqueous solution (c) of the mixed surfactant, the fluorosurfactant should be blended preferably in an amount of 0.01 to 0.1 part by weight. If the amount of the fluorosurfactant is less than 0.01 part by weight, the detergency effect is reduced, which is not preferable. On the other hand, if it exceeds 0.1 part by weight, excessive foaming occurs, which is not preferable. It is more preferable that the fluorosurfactant be blended in an amount of about 0.01 to about 0.08 parts by weight.
The clear liquid detergent of the present invention can be obtained by adding the above sodium silicate solution (a) to the mixed surfactant solution (b) or (c), and mixing fatty acid alkanolamide to thus obtained clear mixture. Here, it is most preferable to blend the sodium silicate solution (a) in an amount of 10 to 35% by weight, the mixed surfactant solution (b) or (c) in an amount of 89.5 to 59% by weight, and fatty acid alkanolamide in an amount of 0.5 to 6% by weight. When the amount of fatty acid alkanolamide is less than 0.5% by weight, no effect results, whereas when it exceeds 6% by weight, the viscosity increases abruptly, which is not preferable. It is more preferable that fatty acid alkanolamide be blended in an amount of 1 to 4% by weight.
It is most preferable that the clear liquid detergent of the present invention contain liquid sodium silicate in an amount of 4.5 to 13.2% by weight.
The sodium silicate-containing clear liquid detergent, thus obtained, maintains its transparency of a so-called crystal-clear type, that it does not generate a deposit or precipitate (precipitates such as silica deposited from sodium silicate, and sodium sulfate by the reaction between the surfactant and the alkali) under the usual use conditions and does not create cloudiness even the temperature varies. Further, in terms of detergency power, it is far superior to the conventional detergent. As described, the clear liquid detergent composition of the present invention exhibits an excellent detergency power in washing of clothes, and cleaning of a washing niche, toilet, bathroom including a bath tub. Further, when diluted with water, the detergent exhibits an excellent power for cleaning dishes. For example, in the case where the clear liquid detergent of the present invention is used for washing clothes, it is preferable that the detergent of the present invention be dissolved at a ratio of 0.8 to 1.0 g per IL (liter) of water.